This is a competing continuation application for renewal of a training program in gastroenterology that was first funded in 1999. The objectives of this program are to provide research training for young investigators committed to a career in investigative gastroenterology or allied fields. The types of research training include basic, translational or clinical research, or combinations of these. Trainees may be MDs, MD-PhDs or PhDs who have finished clinical or graduate training and are seeking further research training in gastroenterology. The training period will last two to three years. Training will consist primarily of mentored research that will provide intense hands-on experience in research methods and experimental design, techniques of data collection, data interpretation including appropriate statistical analysis and preparation of research results for presentation and publication. An extensive menu of didactic courses, workshops, seminars and conferences will also be available. Trainees will be supervised by experienced research mentors with a wide range of interests and expertise from basic cellular and molecular biology to clinical research. A training committee composed of Drs. Lamont, Kelly, Afdhal, and Terhorst and one or two other training faculty will monitor each trainee's research progress. An extensive menu of didactic courses, workshops, seminars and conferences will also be available. The major areas of research available for training include: 1.) Pathophysiology of intestinal inflammation and infection, 2.) Immune mechanisms of bowel disease, 3.) Cellular and molecular abnormalities in intestinal cancer, 4.) Enteric infections, 5.) Receptor biology in hepatic and intestinal diseases, 6.) Mucosal immunity of the gastrointestinal tract, 7.) Hepatic fibrosis, 8.) Regulation of nutrient intake, 9.) Vaccine development and 10.) Genetic factors in GI diseases. The training program will take advantage of the outstanding GI research base within the GI Division and in other laboratories in the Departments of Medicine and Surgery. The training program will also benefit from the availability of a well organized and funded Clinical Research Center at this medical center, as well as the close proximity of two Digestive Disease Centers, one at Harvard Medical School and a second at Massachusetts General Hospital.